New tertiary phosphine oxides and process for their preparation

ABSTRACT

Tertiary phosphine oxides of the formula   WHEREIN R1 and R2 represent identical or different alkyl groups having from 1 to 6 carbon atoms, and R3 represents a phenyl group substituted by 1 to 5 chlorine and/or bromine atoms or the group   IN WHICH X is chlorine and/or bromine, m is 1 to 4, R4 and R5 are hydrogen or alkyl groups having from 1 to 6, carbon atoms, and in formulae I and II n is 1, 2 or 3, and a process for the preparation of the phosphine oxides named and their use as flame retarding agents.

Uited States Kleiner et al.

atet H [451 June 10, 1975 NEW TERTIARY PHOSPHINE OXIDES AND PROCESS FOR THEIR PREPARATION [75] Inventors: I-lans-Jerg Kleiner, Bad Soden Taunus; Walter Diirsch, Schneidhain, Taunus; Gerhard St'ahler, Frankfurt am Main; Werner Racky, Wiesbaden, all of Germany [73] Assignee: Hoechst Aktiengesellschaft,

Frankfurt am Main, Germany [22] \Filed: Nov. 28, I973 \[2l] Appl. No; 419,549

Primary Examiner-Arthur P. Demers Attorney, Agent, or FirmCurtis, Morris & Safford [57] ABSTRACT Tertiary phosphine oxides of the formula wherein R and R represent identical or different alkyl groups having from 1 to 6 carbon atoms, and R represents a phenyl group substituted by l to 5 chlorine and/or bromine atoms or the group in which X is chlorine and/or bromine, m is 1 to 4, R and R are hydrogen or alkyl groups having from 1 to 6, carbon atoms, and in formulae I and II n is l, 2 or 3, and a process for the preparation of the phosphine oxides named and their use as flame retarding agents.

8 Claims, No Drawings NEW TERTIARY PHOSPHINE OXIDES AND PROCESS FOR THEIR PREPARATION The present invention concerns new tertiary phosphine oxides and process for their preparation.

It is already known to react trischloromethylphosphine oxide with sodium phenolate, according to which for example (C H OCH P(O)CH CI can be prepared German Patent 1,230,800). It is further described in USSR-Patent No. 173,765 to react methylbischloromethyl-phosphine oxide with sodium phenolate in an inert solvent in an 83.3 yield to CH P(O) z s slz- The present invention concerns tertiary phosphine oxides of the general formula wherein R and R represent identical or different, preferably identical, alkyl groups having from 1 to 6, preferably from l to 3 carbon atoms, and R represents a phenyl group preferably substituted by l to 5 chlorine and/or bromine atoms or the group in which X is chlorine and/or bromine, m is 1 to 4, preferably l or 2, R R are as above and R and R hydrogen atoms or alkyl groups having from 1 to 6, preferably from l to 3 carbon atoms, in formulae I and 11 n being 1, 2 or 3.

Especially preferred of the compounds of the general formula 1 are those in which R and R and, in the case where R is a group of the formula 11, also R and R represent the methyl group.

The present invention concerns further a process for the preparation of compounds of the formula I, wherein dialkyl halogeno-alkyl-phosphinic oxides of the formula wherein R R and n have the above significance and Hal represents a halogen atom, preferably chlorine or bromine, are reacted with alkaline or alkaline earth metal salts of phenol or phenols substituted by from 1 to 5 chlorine and or bromine atoms or of bisphenols of the formula the alkaline or alkaline earth metal halide formed is filtered off and the compound of the formula I formed is isolated in known manner.

The dialkylhalogenoalkyl-phosphine oxides used as starting compounds can be prepared according to the process of German Offenlegungsschrift 2 060 217. Suitable phosphine oxides are for example: dimethylchloro-methyl-phosphine oxide, dimethylchloroethylphosphine oxide, dimethyl-chloropropyLphosphine oxide, methylethylchloromethyl-phosphine oxide, diethylchloromethylphosphine oxide, di-n-hexylchloromethyl-phosphine oxide.

As starting phenols the following compounds may be considered: phenol, 4-bromophenol, 2,4dichlorophenol, 2,2,6-trichloro-phenol, 2,4,6-tribromophenol, pentachloro-phenol,pentabromo-phenol, 4,4'-isopropylidene-bis-phenol, 4,4-isopropylidene-bis-(2,6- dibromophenol), 4,4-isopropylidene-bis-( 2,6- dichloro-phenol).

Suitable salts of these phenols are the alkaline and alkaline earth metal salts, preferably the sodium or potassium salts or also the calcium or magnesium salts. Of course, these salts can also be prepared in situ, for example by adding an alkaline or alkaline earth metal hydroxide, such as NaOH, KOH, Mg(Ol-l) or Ca(OH) or also the corresponding oxides or carbonates, to the reaction mixture of halogenophosphine oxide and pheno].

The compounds of the invention are preferably prepared in the presence of an inert solvent, such as ethanol, propanol, butanol, glycol, acetonitril, dimethyl formamide, water, chlorobenzene, toluene, dichlorobenzene. Optionally also the reaction product can be used as solvent or as co-solvent. The suitability of solvents is surprising, in which the phenol salts are insoluble, such as chlorobenzene, in which, however, the solubility for phenol salts is increased considerably by the presence of the phosphine oxide.

The reaction is carried out at temperatures of approximately 50 to 250C preferably from C to C. The reaction can also be carried out under pressure whereby the reaction time can be reduced.

The reaction partners can be added to the reaction in arbitrary sequence. After the conclusion of the reac tion, generally the alkali metal halide is separated by filtration. The filtrate is subsequently worked up in known manner. If the reaction product is difficultly soluble in the solvent used in the reaction the separated alkali metal halide is preferably filtered off at an elevated temperature and then the reaction product is isolated from the cooled filtrate by renewed filtration.

The reaction products can be purified in the usual way by distillation or crystallization.

The compounds of the invention are used as flame retarding agents in the preparation of flame resistant linear polyesters (cf. Patent application Ser. No. 419,528 filed concurrently herewith). They have the advantage over the halogen containing organophosphorus compounds, known up to now and used for the finishing of polyesters of a higher thermal stability 3 and very good workability. They can be admixed with the polyesters, during or after the polycondensation, and give them an excellent flame protection when used in quantities of approximately 3 to 20 percent by weight, calculated on the polyesters.

The following examples illustrate the invention.

EXAMPLE 1 126.5 g (1 mol) of dimethylchloromethyl-phosphine oxide. 94 g (1 mol) of phenol and 40 g (1 mol) of sodium hydroxide were kept boiling while stirring in 500 ml of isopropanol for 3 days, then suction filtered. The filtrate was freed by distillation from propanol and water in the water jet vacuum. The residue was distilled. 160 g of dimethylphenoxymethylphosphine oxide were obtained. Boiling point 0.5 l-lg 145C. melting point: 60 64C. This corresponded to a yield of 87 7a of the theory.

C H O P molecular H OC H Calculated: 16.85 P; found: 16.7 P.

EXAMPLE 2 Calculated: 28 78 C1; 12.25 %P; found: 27.7 70 Cl; 12.2 /vP EXAMPLE 3 24 g (0.19 mol) of dimethylchloromethyl-phosphine oxide and 37 g (0.19 mol) of sodium salt of 4- bromophenol were refluxed while stirring for 6 hours in 200 ml of acetonitril. Then the precipitated sodium chloride was separated by suction filtration from the mixture and the filtrate was free from acetonitril extensively in the waterjet vacuum. The residue crystallized. 48 g of dimethyl-4-bromophenoxymethyl-phosphine oxide were obtained, corresponding to a yield of 96 "/0 of the theory. By recrystallization from benzene the phosphine oxide was purified. Melting point: 119 121C.

molecular weight 263 (Cl-1 1 Ptolcl'l mw Calculated: 30.4 Br; 11.8 P: found: 30.1 Br; 1 1.8 P.

EXAMPLE 4 57.5 g (0.454 mol) of dimethylchloromethylphosphine oxide and g (0.454 mol) of the sodium salt of 2,3,6-trichlorophenol were refluxed while stirring together with 500 ml of dimethylformamide. After 5 hours the reaction mixture was cooled. The separated sodium chlodie was filtered off and the filtrate was freed by a distillation in the water jet vacuum extensively from dimethyl formamide. 124 g of dimethyl- 2,4,6-trichlorophenoxymethyl-phosphine oxide remained, this corresponded to a yield of 95 of the theory. The product can be recrystallized from cyclohexane. melting point 121 126C.

molecular weight 287.5

Calculated: 37.1 Cl; 10.8 P; found: 37.1 Cl; 10.8 P

EXAMPLE 5 52.5 g (0.415 mol) of dimethylchloromethyl phosphine oxide and g (0.41 mol) of sodium salt of pentachlorophenol were refluxed while stirring vigorously in 500 m1 of chlorobenzene for 7 hours. Then the mixture was filtered off from the precipitated sodium chloride and the chlorobenzene was eliminated extensively by a distillation in the water jet vacuum. The residue was recrystallized from ethanol. 110 g of dimethyl-pentachlorophenoxymethyl-phosphine oxide were obtained. Melting point 207C 210C. This corresponded to a yield of 74.5 of the theory.

C ll Cl O P molecular weight 356.5

Calculated: 49.8 Cl; 8.7 P; found: 50.5 Cl; 8.4 7: P.

EXAMPLE 6 39.5 g (0.312 mol) of dimethylchloromethylphosphine oxide and 1 11 g (0.312 mol) of sodium salt of 2,4,6-tribromophenol were stirred into 400 ml of di methylformamide at 140C for 6 hours. Subsequently the mixture was drawn off from the sodium chloride and the filtrate was freed from dimethylformamide extensively by a distillation in the water jet vacuum. The residue was recrystallized from a litle cyclohexene. 92 g of dimethyl-2.4,(tribromophenoxymethyl-phosphinic oxide were obtained. Melting point 129C. This corresponded to a yield of 70 7a of the theory.

molecular weight 421 1 P lOlCH OQ-B lBr EXAMPLE 7 50.5 g (0.4 mol) of dimethylchloromethylphosphinic oxide and 1208 g (0.4 mol) of sodium salt of pentabromophenol were heated to boiling in 500 ml of chlorobenzene for 15 hours while stirring vigorously. Subsequently the mixture was filtered off at 120C. in the cold the reaction product crystallized from the chlorobenzene and was filtered off. By concentrating the mother liquor further reaction product was gained. The raw product was recrystallized from isopropanol with the addition of water. 175 g of dimethylpentabromophenoxymethyl-phosphine oxide were obtained. Melting point approximately 245C. This corresponded to a yield of 76 of the theory.

C H Br O P molecular weight 575 Br Br 101 HolcrgoQm 1B Br Calculated: 69.2 Br; 5.35 9% P; found: 70.1 Br; 5.3 P.

EXAMPLE 8 Calculated: 25.3 Cl; 11.05 P; found: 24.5 Cl; 10.9 1P.

EXAMPLE 9 93 g 1.10.735 mol) of \dimethylchloromethylphosphine oxide and 100 g (0.368 mol) of disodium salt of 4,4'-isopropylidenebisphenol were refluxed while stirring with 400 ml of chlorobenzene for 5 hours. Subsequently, the mixture was filtered off from the precipitated sodium chloride and the filtrate was freed extensively l'rom chlorobenzene by a distillation in the water jet vacuum. The residue was recrystallized from acetone. 120 g of the derived phosphine oxide were obtained. Melting point 142C 148C. This corresponded to a yield of 80 of the theory. 5 2l 30 -l 2 molecular weight 408 Ca1c.: 15.2 P;

I 3 (CH3)2P(0)CH2O c 6 0Cl-l P(0)(Cl-l found: 14.9 P.

EXAMPLE 10 63.9 g (0.505 mol) of dimethylchloromethylphosphine oxide, 136 g (0.25 mol) of 4,4- isopropylidene-bis-(2,6-dibromophenol), 61.2 g (0.505 mol) of a 33 solution of caustic soda were dissolved while stirring at 60C in 100 ml of water. To this 150 ml of xylene were added and 150 ml of water were distilled off a azeotropically. After adding 550 g of chlorobenzene the mixture was refluxed for 10 hours and subsequently filtered off while still hot from the precipi' tated sodium chloride. From the filtrate crystals were separated. these were filtered off and washed well with ethyl acetate. 145 g of the desired phosphine oxide were obtained after drying. This corresponded to a yield of 80 of the theory. The product could be recrystallized from benzene. Melting point 208 209C.

molecular weight 724 Br (2H Br lCH P(O)CH2OQ(II OCH2P(O)(CH3)2 Br 3 Br Calc.: 44.1 Br; 8.6 P; found: 43.2 Br; 8.3 P. What is claimed is:

wherein R and R represent alkyl groups of l to 6 carbon atoms and may be the same or different and R represents a phenyl group which may be substituted by l to 5 chlorine and/or bromine atoms or the group having the general formula in which X is selected from chlorine and'bromine, n1 is '10 l to 4, R and R are as defined above, R and R are hydrogen atoms or alkyl groups of l to 6 carbon atoms, and n is l to 3.

2. A tertiary phosphine oxide of the general formula P CH R R wherein R and R represent alkyl groups of l to 3 car bon atoms and may be the same or different and R represents a phenyl group substituted by l to chlorine and/or bromine atoms or is the group of the general formula:

[l R i 4{ -O-(CH2) -P l in which X is selected from chlorine and bromine, m is l to 4, R, and R are as defined above, R and R are hydrogen or alkyl groups of l to 3 carbon atoms, and n is l to 3v 3. A tertiary phosphine oxide according to claim 1 wherein R and R are methyl, n is l and R is halophenyl.

4-. A tertiary phosphine oxide according to claim 3 wherein R is chlorophenyl.

5. A tertiary phosphine oxide according to claim 3 wherein R is bromophenyl.

6. A tertiary phosphine oxide according to claim 1 of the formula:

CH l 3 (CH3)2P(0)CH2O -T- Q 0CH P( CH3 7. A tertiary phosphine oxide according to claim 1 0f the formula:

8. A process for the preparation of a tertiary phosphine oxide which comprises'reacting a dialkylhaloal- I kyl phosphine oxide of the formula:

P'- (Cl-l Hal wherein R and R represent alkyl groups of 1 to 6 carbon atoms and may be the same or different, n is l to 3', and Hal represents a halogen atom, with an alkaline or alkaline earth metal salt of phenol or of a phenol substituted by l to 5 halogen atoms selected from chlo rine and bromine atoms or an alkaline or alkaline earth metal salt of a bis-phenol of the formula:

to form a dialkyl-phenoxyalkyl phosphine oxide and an alkaline or alkaline earth metal halide, separating the metal halide by filtration and recovering the dialkyl phenoxyalkyl phosphine oxide. 

1. A TERTIARY PHOSPHINE OXIDE OF THE GENERAL FORMULA
 2. A tertiary phosphine oxide of the general formula
 3. A tertiary phosphine oxide according to claim 1 wherein R1 and R2 are methyl, n is 1 and R3 is halophenyl.
 4. A tertiary phosphine oxide according to claim 3 wherein R3 is chlorophenyl.
 5. A tertiary phosphine oxide according to claim 3 wherein R3 is bromophenyl.
 6. A tertiary phosphine oxide according to claim 1 of the formula:
 7. A tertiary phosphine oxide according to claim 1 of the formula:
 8. A process for the preparation of a tertiary phosphine oxide which comprises reacting a dialkylhaloalkyl phosphine oxide of the formula: 